Chronic reflux (heartburn) damages the lining of the esophagus by repeatedly exposing it to stomach acid This damage is believed to lead to the replacement of the normal stratified squamous esophageal lining with a columnar mucosal tissue. The conversion of the normal lining tissue to columnar tissue is called Barrett's metaplasia.
Barrett's metaplasia is a precursor and an important risk factor for cancer of the esophagus. About 25 million Americans suffer persistent chronic heartburn, and 10% of those will develop Barrett's metaplasia. Patients with Barrett's metaplasia are from 10 to 125 times more likely to develop cancer of the esophagus than the general population Cancer of the esophagus is fairly common, with about 30,000 cases per year currently reported in the United States. Cancer of the esophagus is also deadly, with a five-year survival rate of about 7%.
Currently, Barrett's metaplasia is diagnosed by endoscopy once symptoms have become severe enough to demand endoscopy examination However, at this point, about 5% to 10% of the patients endoscopically examined and found to have Barrett's metaplasia already have cancer of the esophagus. Unfortunately, endoscopic examination for Barrett's metaplasia is too expensive and time-consuming for routine mass screening of patients suffering persistent chronic heartburn. If a feasible and cost-effective technique could be developed for detecting Barrett's metaplasia before it has progressed to cancer of the esophagus, it would be possible to monitor patients with Barrett's metaplasia periodically, such as every six months to two years, to detect a transition to precancer (dysplasia) or to esophageal cancer at an early stage. Early detection of esophageal cancer would improve the rate of survival because esophageal cancer, when diagnosed at an early stage, is more likely to be surgically curable than when diagnosed at an advanced stage.
The lining of a normal esophagus is pearly white, while the lining of a normal stomach is salmon pink. The white-to-pink junction normally occurs at a depth of 39 to 41 cm from the teeth of a patient In patients with Barrett's metaplasia, the white-to-pink junction may occur 21 to 25 cm from the teeth of the patient. At this level the color changes from white to pink, a junction called the ora serrata. The abnormally high location of this transition is normally used to diagnose Barrett's metaplasia during endoscopic examinations. If the ora serrata is located unusually high in the esophagus, biopsies are taken of the lining below the ora serrate. These biopsies are examined with a microscope to make a diagnosis of Barrett's metaplasia. The endoscopic examination must be performed carefully by a highly trained and experienced endoscopist. It is not currently realistic to attempt to screen all patients with heartburn endoscopically because of limitations in personnel, time involved in cleaning the endoscope and expense.
In summary, there is currently no quick, relatively inexpensive screening technique that could be used by relatively untrained medical practitioners to detect Barrett's metaplasia. As a result, no feasible and cost-effective means currently exist for the mass screening of reflux esophagitis patients in order to detect Barrett's metaplasia